1. Field of the Invention
The present invention relates to a method and apparatus for providing motion control signals between a fixed camera and a PTZ camera, and, more particularly providing motion control signals between a fixed camera and a moving PTZ camera for detecting a moving object and taking a picture of the moving object.
2. Background of the Invention
It is desirous for surveillance systems to monitor a wide area, as well as capture detailed information about any suspicious target within that wide area. Practically, however, this is very difficult to achieve, since the goal of wide area monitoring and high resolution target image acquisition are opposite. This is since a wide area monitoring system needs a camera lens with a large field of view, and thus a short focal length, but to identify an object at a distance, a telephoto lens that has a small field of view and a large focal length is needed. FIG. 1A illustrates a picture taken with a camera having a wide angle lens with a short focal length, and FIG. 1B illustrates a picture of an object with the field of view of FIG. 1A taken with a camera having a telephoto lens to illustrate these opposing considerations.
In addition to using a telephoto lens, if substituting the telephoto lens, which has a fixed focal length, for a zoom lens, which has a range of larger focal lengths, the technical complexity increases even further.
It is known, however, to use a side-by-side combination of cameras together within a surveillance system, such as a fixed view wide angle camera mounted next to a zoom camera For example, the article entitled “A Master Slave System to Acquire Biometric Imagery of Humans at a Distance” by Xuhui Zhou et al; IWVS, 2003; Nov. 7, 2003 describes a system that includes a master camera having a wide angle lens, a slave camera having a fixed-in-use zoomed lens next to it, and a pan-tile-zoom (PTZ) process that is used to control movement of the slave PTZ camera based upon information received from the master camera and the slave camera. While this system describes basic elements that are known in such surveillance systems, the PTZ process as described has disadvantages.
One disadvantage with known dual rig cameras, such as the one described above, is that manual calibration between the different cameras is required. In this manual calibration, first a series of pixel locations are picked up. Then for each of those pixels, the PT camera is moved manually to center at that pixel and the P/T values are recorded. After manually calibration all those preselected points, interpolation was used to get a denser map. This process is tedious and requires significant human effort. And this process is performed every time a different lens and every time a different configuration is used. Further, the system requires regular calibration after the deployment due to slight physical shifts between the two cameras.
While the above methods of use and configurations of dual rig cameras are useful, improvements to make them more durable, efficient and cost-effective are needed.